Patent Document 1 discloses a power conversion apparatus capable of performing step-up and -down operations. This power conversion apparatus makes four switch elements continuously perform switching operations in order to suppress a spike occurring at the switching between step-up and step-down operations. More specifically, two switch elements Q1 and Q2 provided on the side of an AC end perform a step-down operation by switching at a constant duty.
The configuration in the related art has a large switching loss because the switch elements continuously perform switching operations. In particular, the two switch elements Q1 and Q2 provided on the side of the AC end have a large switching loss.
When viewed from a different viewpoint, an input current from the AC end is interrupted by the switching operations of the two switch elements Q1 and Q2 provided on the side of the AC end. A reactor current flowing to a reactor is therefore large. As a result, a reactor loss is increased due to the large reactor current. Further, a conduction loss and a switching loss of the switching elements are further increased due to the large reactor current.
Patent Document 1: Japanese Patent No. 3825386 (JP-A-2004-135372)